block: saner flags filtering in bdrv_open2

Clean up the current mess about figuring out which flags to pass to the
driver.  BDRV_O_FILE, BDRV_O_SNAPSHOT and BDRV_O_NO_BACKING are flags
only used by the block layer internally so filter them out directly.
Previously BDRV_O_NO_BACKING could accidentally be passed to the drivers,
but wasn't ever used.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Christoph Hellwig 2010-01-28 15:19:12 +01:00 committed by Anthony Liguori
parent eaa6c85f5d
commit 15dc2697a5
1 changed files with 14 additions and 7 deletions

21
block.c
View File

@ -451,13 +451,20 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags,
bs->enable_write_cache = 1;
bs->read_only = (flags & BDRV_O_RDWR) == 0;
if (!(flags & BDRV_O_FILE)) {
open_flags = (flags & (BDRV_O_RDWR | BDRV_O_CACHE_MASK|BDRV_O_NATIVE_AIO));
if (bs->is_temporary) { /* snapshot should be writeable */
open_flags |= BDRV_O_RDWR;
}
} else {
open_flags = flags & ~(BDRV_O_FILE | BDRV_O_SNAPSHOT);
/*
* Clear flags that are internal to the block layer before opening the
* image.
*/
open_flags = flags & ~(BDRV_O_FILE | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
/*
* Snapshots should be writeable.
*
* XXX(hch): and what is the point of a snapshot during a read-only open?
*/
if (!(flags & BDRV_O_FILE) && bs->is_temporary) {
open_flags |= BDRV_O_RDWR;
}
ret = drv->bdrv_open(bs, filename, open_flags);